Problem: Omar ate 4 slices of cake. Vanessa ate 3 slices. If Omar ate $\dfrac{4}{12}$ of the cake, what fraction of the cake was eaten?
If 4 slices represent $\dfrac{4}{12}$ of the cake, there must have been a total of 12 slices. $\text{fraction of cake eaten} = \dfrac{\text{number of slices eaten}}{\text{number of slices total}}$ They ate ${7}$ out of $12$ slices. They ate $\dfrac{7}{12}$ of the cake.